Testing of well drilling mud



May 1, 1962 E. J. DOWER 3,031,89I

TESTING OF WELL DRILLING MUD Filed Aug. 17, 1959 2 Sheets-Sheet 1 INV EN TOR.

QC (MW ATTORNf/ May 1, 1962 E J. DOWER TESTING OF WELL DRILLING MUD 2 Sheets-Sheet 2 Filed Aug. 17, 1959 Dan er INVENTOR.

BY /c1\uw United States Patent 3,031,891 TESTING OF WELL DRILLING MUD Ethell J. Dower, Houston, Tern, assignor to ,Warren Automatic Tool Company, Houston, Tex., a corporation of Texas Filed Aug. 17, 1959, Ser. No. 834,192 4 Claims. (Cl. 73-438) This invention relates 'to the drilling of wells with rotary bits involving the circulation of liquid mud down through the drill pipe string and back through the open hole to the surface and more particularly to instrumentation for measuring mud density at a selected circuit location. A common practice is to weigh occasional samples of returning mud and note comparative changes as calling for modification of entering mudco'mposition or as indicative of significant down hole occurrences.

It is an object of the present invention to provide improved sampling equipment whereby automatically acting controls harness pneumatic pressures for a continuing operation of measuring samples taken at close time intervals from a mud stream.

A further object of the invention is to provide a simplified sampling chamber and controls for cycling in repeated sequence the phases of induction and eduction through the chamber entrance and discharge mouth of mud columns from a flowing stream together with instrumentation for reading differential head pressures at spaced apart points in the chamber contained column as an indication of density composition.

Another object of the invention is to provide dependable control valving devices for directing pneumatic pressures through rapid cycles of predetermined durations and involving a chamber air evacuating phase in which a mud sample to be tested is drawn into the chamber to a given level whose attainment is utilized for effecting an air pressuring phase in which the tested sample is forcibly and completely ejected in readiness for the intake of an entirely new sample and immediate repetition of the cycle.

Other objects and advantages of the invention will become apparent during the course of the following specifications having reference to the accompanying drawings in which FIG. 1 is a schematic view of the test equipment as set up for operation; FIG. 2 is a perspective view of the sampling chamber and interconnected control components; FIG. 3 is a vertical sectional view of the pilot valve detailed structure on a large scale; FIG. 4 is a vertical sectional view through the upper portion of the sampling chamber; FIG. 5 is a sectional detail, and FIG. 6 is a diagrammatic representation of a complete installation of the system with the sample chamber filled with liquid mud to be weighed.

Referring to the drawings the sampling chamber is contained within an upper deadended container 1, open at its bottom for submergence at all times below the top surface of aliquid, illustrated as a flowing stream within a flume 2. -Depth of submergence is unrelated to operation so long as the bottom entrance and discharge mouth remains covered. The container 1 preferably is a thin wall cylindrical aluminum casting having a pair of side mounting bosses 3 and projected studs 4 to receive suitable clamping caps for attachment to a vertical stand or post; A detachable cover plate 5 closes the upper end of the cylinder and is shown as being held down by hand nuts 6 screw-threaded on swingable studs hinged to the cylinder wall.

Spaced downwardly below its upper end the container side wall provides communication with a pair of vertical- 1y spaced apart flexible pressure transmitting horses or conduits 9 through upper and lower side wall openings 7 shown respectively in FIGS. 4 and 5. The detail of the openings is identical and each is covered exteriorly by a hollow fitting 8 welded or otherwise fastened to the wall to afford a small upwardly extended pocket whose upper end is for detachable connection with a threaded hose terminal. The opposite terminals of the two hoses are connected with and are deadened on opposite sides of a flexible diaphragm or movable partition between sealed chambers within a hollow housing 10 constituting one component of a converter assembly 11 operatively coupled to a recorder 12. The partitioned housing 10 is a conventional commercial unit whose diaphragm moves in response to differential pressures on opposite sides. Differential pressures are transmitted to the housing by air columns entrapped or contained within the relatively short hoses leading from the vertically spaced apart side openings 7. Unless liquid mud is contained within the sampling chamber there willbe no appreciable differential pressure but a pressure difference will occur, for example, when the mud column extends above both openings. A vertical spacing of about seventeen inches between the openings 7 will provide a maximum differential head consistent with rapid cycling.

The density of the mud is determined from the differ- I ential pressure at two port 7 vertically spaced on the side of the mud chamber. As air is removed from the container the pressure is reduced below atmospheric in both port fitting chambers. As the mud level rises and covers the lower port no more air is removed therefrom. The pressure (below atmos.) thus established is a function of the density of the mud and the head or elevation above the level of the mud exposed to atmospheric pres sure outside the sample chamber. As air continues to be removed from the chamber and the pressure reduced in the upper port 7 a differential pressure is created between the two ports. A the mud covers the top port the pressure established in it is also a function of the density of the mud and its head or elevation above the outside mud level. Hence, the difference between these two'pressures is a function of mud density and the'head between'the ports. The head between ports is a constant and the difference in pressures is a direct function of density.

While response to the differential pressure diaphragm within the housing 10 can be registered directly on a recorder it is desirable to eliminate the showing-of the entire wide range of fluctuation from zero-during the time the chamber is empty to relatively high figures in the weighing phases of the cycles and to obtain only a higher band reading representative of wanted sample weight values. able pressure difierential pressure converter 11 is introduced between the diaphragm device .111 and a standard recorder 12 and serves to provide pneumatic operating force at the recorder proportional to wide differential pressures at the diaphragm. A simple pneumatic system includes a'pressure air storage tank from which pressure air is valved to -a recorder connected air column and is influenced by force transmitted through a pivoted beam from the diaphragm device 10 and opposed by a predetermined elastic restraint in a portion of the range whereby recordings of column pressures show differential diaphragm force Within a fairly narrow high band in the range.

Enclosed within the top of the sample chamber is a liquid level responsive float 13 whose action establishes' maximum level of sampling liquid and sets in action the start of the liquid ejection phaseof the automatic cycle. The float 13 is illustrated as consisting of a hollow box to be buoyed upwardly from a lower limit at least slightly above the uppermost of the two ports For that purpose, a commercially avail-.

3 Secured over the lower end of the hollow stem 16' is a closure disc 17 extended peripherally beyond the stem as a rim serving as a retainer and downward limit stop for the magnet ring and float assembly. A cylindrical skirt 18 fastened on the underside of the cover plate surrounds the magnet assembly as a protective shield or bathe against splashings. The top of the skirt 1% is .sealed to the cover plate 5 and the skirt enclosed space affords a dead pocket to resist entry of mud should mud level rise abnormally into the top of the chamber. The. co-o'perating surfaces of the float carried magnets and tube 16 are thus protected from mud cake deposit to interfere with free operation.

The tubular stem 16 affords an upwardly opening well sealed oil from the interior of the sample chamber. Slideably housed within the Well is a plunger including an upper stem portion 19 and a lower magnet rod portion 20 for cooperation with the ring magnets 15 in affording a coupling for the transmission of float travel to the reciprocatory stem 19.

The upstanding stem 19 extends through a shouldered guide disc 21 and carries therebeyond a terminal head 22 having a lateral opening or eye to receive loosely one end of a valve operating lever 23. At its opposite end the lever 23 has a rounded corner to rock or fulcrum on the upper surface of a pilot valve housing 24 bracketed on the top plate 5. Spaced from the rocking corner of the lever 23 is a pivot pin connection with the upper end of a pilot valve 25 comprising a guide stem and a head for cooperation with a mating valve seat Within the housing 24. A coil spring 26 grounded interiorly of the housing acts on the valve head to oppose its opening movement under force transmitted through the float connections upon float elevation. A protective hood or cap 27 as seen in FIG. 2 encases the pilot valve and its operating linkage.

Normally the pilot valve 25 is in the closed position illustrated and is momentarily opened once in each cycle as the float rises for the-relatively short time between the end of a sample induction phase and the beginning of a sample eduction phase. As will be explained, the valve initiates shift from evacuation ofair from thesample chamber to the delivery of air under pressure to blow out the whole previously tested liquid sample. The inlet side of the valve housing 24 is coupled as best seen in FIG. 2 through a hose or pipe 28 to one leg of a T fitting 29 through which a supply of pressure air is delivered from an available source. Preferably a restrictive orifice is included ahead of the pilot valve 25 to accommodate a quick shot of high pressure air beyond the valve for a short opening interval but without either prolongation of high pressure flow or back flow diminution of pressure beyond the orifice.

The third leg of the T fitting 29 is coupled to an aspirator tube 30 having a suction nozzle arrangement. The outlet from aspirator tube 30 includes a valve housing 31 containing a control valve (see FIG. 6) which when in open position allows passage of pressure air through the aspirator for creating a partial vacuum which is utilized as the motivating force in the sample induction phase of the operating cycle. The action of the aspirator induces air flow through a connecting pipe or sample chamber vacuum connection 32 leading behind the nozzle from the top of the sampling chamber space for the evacuation of chamber air and its replacement by, liquid mud rising upwardly through the submerged lower open end of the container 1 under atmospheric pressure and until the mud column covers both side openings 7 and reaches a level established by the location of the 7 quick shot ofpressure air through a pipe line 33' for expanding a variable volume chamber of a" pneumatic motor formed by a tubular shell 34 and a movable wall or partition such as a sliding piston 35 (see'FlG. 6)

having coupled connection with the valve 36 to control closing of the outlet vent from the housing 3].. Closure of the housing vent upon depression of the piston 35, discontinues the aspirating effect and instead deflects air travel outwardly through the pipe connection 32. With reversal of pressure flow direction within the connecting tube 32 pressure air is delivered at a rapid rate into the sample chamber and quickly blows out the tested sample. The control float 13 drops immediately and closes the pilot valve. Duration of pressure flow is timed not only to clear out all of the liquid mud sample but also to continue the delivery of air pressure long enough to rid the interior of the sample chamber of floating foam. As a result of thorough clean-out there is assured that no part of the previous sample will be taken back into the chamber on the next succeeding intake phase.

Immediately following the start of the ejection phase the pilot valve 25 will snap shut as the float descends with level drop'in the sample chamber and thereafter the pressure air within the variable capacity pneumatic motor chamber above the piston 35 and which had caused piston depression will bleed off to atmosphere through a metering constriction or orifice 37 of predetermined size relative to prevailing pressure levels within the piston cylinderand the force of a piston return spring 38 acting in opposition to pressure-air on the piston. This slow bleed ofi delays reopening of the valve 36 for a short interval to complete the eduction phase of the cycle but finally when the valve is again unseated the open vent from the housing 31 re-establishes the aspirating action for the start of an induction of another sample to be tested. The equipment is so constructed that automatic cycling takes place repeatedly in selected intervals of from thirty to sixty. seconds.

In the diagrammatic illustration of FIG. 6 there is shown interposed in the reverse flow line 32 a moisture collecting bottle 39. The portion of the line between the aspirator tube 369 and the bottle ends near the top of the bottle while the pipe line portion between the bottle and the sample chamber extends downwardly to end a short distance from the bottom of the bottlel Liquid may on occasion be drawn into the bottle fof temporary storage and return to the sample chamber. In use and during the aspirating intervals any moisture or mud particles drawn into the bottle will tend to separate from the air and drop toward entrapment within the bottl On the other hand during reverses of pressure air flow from the aspirator tube 39 toward the sample chamber the air entering the upper region of the bottle will tend to blow moisture upwardly through the long dependent tube and back toward the sampling chamber for dissipation. At infrequent intervals and depending upon the consistency of the liquid mud being used at a particular drilling site there may be enough heavies collected to justify removal of the accumulation by bottle disassembly and replacement.

What is claimed is:

1. Equipment for testing density of liquid samples including a sampling chamber, means to indicate column.

pressures between vertically spaced apart points within the chamber and cycling means connected with the chamber to efitect induction and eduction of a liquid sample, and including a pneumatic reverse flow conduit leading fromthe top of the chamber, an aspirator tube having a pressure air inlet and an outlet in spaced apart relation and being connected with said conduit intermediate the inlet and outlet, a valve to open and close said outlet, a variable volume chamber having a pressure air inlet and a restricted outlet to bleed pressure air therefrom, a pressure responsive movable chamber wall connected with the valve to operate the same, meansbiasing the wall toward valve opening position, an intermittently operated pilot valve controlling the supply or" pressure air to'the chamber inlet and a liquid level float in the sampling chamber connected with said pilot valve to open the same upon attainment of a predetermined liquid level within the sampling chamber.

2. In fluid density measuring equipment, a sampling chamber for the alternate introduction and discharge of fluid samples, indicator mechanism having fluid conduit connections with the chamber at vertically spaced apart levels below the top of the chamber and being responsive to differential fluid pressures in the connections and operating mechanism for alternately charging the chamber with pressure air and withdrawing air from the top of the chamber, comprising an air pressure conduit, an aspirator device in the conduit having an exhaust port and a chamber vacuum connection, a normally open valve operable to close said exhaust port for directing pressure air through said vacuum connection, a pneumatic motor chamber having an air bleed vent and a movable wall connected with said valve to close the same in response to motor chamber pressure air action on the movable wall, spring means exerting valve opening force in opposition to motor chamber air pressure, a pressure air supply connection With the motor chamber, a pilot valve in said air supply connection and float means in the sampling chamber above the levels of said fluid conduit connections and having motion transmitting connection with said pilot valve to cycle the opening and closing of the same with the rise and fall of the float means.

3. Liquid density measuring equipment, including a sampling chamber having a bottom opening to be submerged in a liquid for the entry and expulsion of successive liquid samples, each of which is completely expelled through the bottom opening for minimizing re-entry of previous sample content, a pressure indicator communicating with the chamber at vertically spaced apart heights, a source of air under higher than atmospheric pressure, means active to produce subatmospheric pressure, flow connection means communicating the top of said chamber with the pressure air source and the subatmospheric pressure producing means and cycling mechanism controlling the alternate withdrawal of air from and the delivery of pressure air to said chamber, comprising valve means for said flow connection means, a float contained within the chamber and connected with said valve means to actuate the same when the float is raised by a liquid sample for discontinuing the action of said subatmospheric pressure producing means within the chamber and directing pressure air to and pressurizing the chamber to a value exceeding the liquid head at the depth of submergence of said bottom opening for complete ejection of the liquid sample, an actuator active on the valve means to restore the same to a position re-establishing withdrawal of air from the chamber and means to delay the action of said actuator for eflecting the complete expulsion from the chamber of the entire content of a liquid sample.

4. Fluid density measuring means operating automatically through repeated cycles of accepting and rejecting fluid samples to be measured, including a sampling chamber to receive a fluid sample column and having an inlet and discharge mouth submerged in the fluid to be sampled, a source of air at higher than atmospheric pressure, flow connection means joining said pressure air source with the top of the sampling chamber for delivery thereto of pressure air of a value in excess of the fluid head at the submerged mouth to cause rejection in toto of a sample column through said submerged mouth, air exhaust connection means for the withdrawal of air from the chamber to cause entry therein of a sample column, fluid Weight reading means having connection with the chamber at two vertically spaced apart points below the top of a sample column and reflecting the density of fluid between such points, a sample column actuated float operating within the chamber to regulate the cycle of sample acceptance and rejection, valve means responsive to rise and fall of the float and controlling pressure air delivery and exhaust connection means for sequential delivery and exhaust phases with float rise and fall respectively and means to delay action of the valve means upon fall of the float and thereby prolong the pressureair delivery phase until the fluid head above the submerged depth of said mouth is overcome and the chamber is completely evacuated of the whole sample column content.

References Cited in the file of this patent UNITED STATES PATENTS 1,621,535 Haultain Mar. 22, 1927 2,115,520 Decker Apr. 26, 1938 2,541,102 Rymal Feb. 13, 1951 2,803,963 Condolios Aug. 27, 1957 

